CSLB C-20 HVAC ContractorCooling and RefrigerationHard
A client asks about R-32 refrigerant, which is classified as A2L under ASHRAE Standard 34. What does this classification indicate about the refrigerant?
- ANontoxic and nonflammable
- BNontoxic with lower (mild) flammability
- CToxic and highly flammable
- DToxic but nonflammable
Show answer & explanationAnswer & explanation
Correct answer: B. Nontoxic with lower (mild) flammability
In ASHRAE Standard 34 safety classifications, the letter indicates toxicity (A = lower toxicity, B = higher toxicity) and the number/letter indicates flammability (1 = nonflammable, 2L = lower flammability, 2 = flammable, 3 = highly flammable). A2L therefore means lower toxicity and lower (mild) flammability, requiring special handling precautions like ignition source control that A1 refrigerants (e.g., R-410A) do not.
Why the other options are wrong
- A. A1 (like R-410A) is nontoxic and nonflammable; A2L is mildly flammable, not fully nonflammable.
- C. A2L is lower toxicity (A) and only mildly flammable (2L), not highly flammable.
- D. The 'A' classification specifically denotes lower toxicity, not toxic.
ASHRAE 34 Safety Classification (A2L)
A2L refrigerants like R-32 are classified as lower toxicity (A) and lower flammability (2L) under ASHRAE Standard 34, requiring special handling precautions beyond nonflammable A1 refrigerants.
- Letter = toxicity (A=lower, B=higher)
- Number = flammability (1=none, 2L=lower, 2=moderate, 3=high)
- A2L refrigerants require ignition-source precautions during handling and installation
Memory trick: A is safe from poison, number tells you about fire